In general, a synthetic resin composition is used as a raw material in a variety of fields including household supplies, synthetic fibers, filters, electronic materials and the like and requires functional reinforcement. As is well known, silver is a noble metal, which has no toxicity to humans and removes toxins. Also, the silver is known as a superior natural antibiotic which neutralizes enzymes related to metabolism of 650 or more species of pathogenic microorganisms including bacteria, viruses and mold and thus has an excellent effect on fungi and viruses as well as bacteria uncontrollable by general antibiotics. Therefore, a resin composition containing nano silver particles may be usefully used as an antibiotic resin, an antistatic resin, an electromagnetic wave shielding resin or the like.
The antibiotic resin composition may be utilized as a container for food and beverage, water supplying pipe, a container for a refrigerator, a water tank of a humidifier, a medical container and the like. Also, the resin composition containing nano silver particles dispersed therein may be effectively used as a material for electromagnetic wave shielding in electronic appliances and also widely used as a resin composition for preventing static electricity in home electronics.
In recent, there have been made many efforts to achieve cost reduction and simplified process in preparation of the resin composition containing the nano silver particles by increasing an affinity of the nano silver particles for the synthetic resin composition.
The resin composition containing the nano silver particles may be prepared by a variety of methods. In one example, Korean Patent Publication No. 2005-0047029 discloses a method of dispersing the nano silver particles using a physical force, in which, in a super mixer, polypropylene (PPJ700, Hyosung Corp., Korea) is put and rotated for 40 minutes with the temperature being increased to 55 to 65° C., nano silver particles colloidal solution is then put and rotated again for 20 to 30 minutes, and a wax (product name: X861, Bayer) is put as a dispersing agent and further rotated for 5 to 10 minutes to prepare the resin containing nano silver particles. In another example, Korean Patent Publication No. 2005-0079261 discloses a method of preparing a resin composition containing nano silver particles, in which a conventionally used mixer is heated to be maintained at a constant temperature, and a mixture of an general purpose plastic such as PVC and PE, an engineering plastic such as PET and PC and highly concentrated transparent colloidal silver aqueous solution is then put in the mixer and kneaded with stirring, followed by the extrusion by an extruder while the temperature being maintained suitably at 150 to 300° C. and cutting the extruded product to a predetermined size and shape.
In further another example, Korean Patent Publication No. 2003-0003203 discloses a method of preparing a resin composition containing nano silver particles, in which a synthetic resin composition, silver powder and aluminum powder are mixed and heated to a temperature of 180 to 230° C., followed by stirring by a stirrer to melt mix the silver powder.
According to the conventional methods as described above, a polymer resin composition is previously obtained from a monomer and then dispersed in colloidal solution or solid powder of nano silver particles which has been also previously prepared. Therefore, there are disadvantages that the preparation process is complex and uneconomic since a dispersing agent is needed to facilitate the dispersion and a physical force, e.g. an extruder, a melter, a stirrer or a super mixer is also needed.
Further, Korean Patent Publication No. 2003-0049007 discloses a method of preparing a resin composition containing silver particles by mixing a colloidal solution of nano-sized silver, monomers for a resin composition, an emulsifier and an initiator and then performing emulsion polymerization, suspension polymerization or microemulsion polymerization.
However, since the colloidal solution of nano silver particles is used in this method, an emulsifier or a dispersing agent is needed to facilitate the dispersion of the nano silver particles and there is a limitation in uniformity of the nano silver particles dispersed in the resin composition.
Meanwhile, Korean Patent Publication No. 2003-0031090 discloses a method of preparing unsaturated polyester composite containing nano silver particles, in which silver salt such as silver nitrate and silver acetate is dissolved in polar solvent such as acetonitrile and ethylene glycol and mixed with unsaturated polyester resin composition containing styrene monomer, followed by curing by a radical initiator and an accelerator to prepare the unsaturated polyester composite containing nano silver particles. This method is characterized in that silver ion is reduced and grown to the nano silver particles during radical polymerization. However, polar solvent for dissolving the silver salt is necessarily required since the silver salt such as silver nitrate and silver acetate is used and it is difficult to prepare a resin composition in which the nano silver particles are dispersed with high concentration since there is a limitation in uniformity and dispersibility of the nanoparticles contained in the polymer resin composition.